what turns up in the dark?
by LadyMoriel
Summary: Thanos is dead. Loki might not be, if there's anything Steve can do about it. Steve/Loki; rated for violence/torture. (It's the snake venom thing.)


_Okay, so, I originally started this for Stoki Week way the hell back in July and it was supposed to be a quick thing (which I would have dedicated to Lise on AO3 at the time because she's the reason I like this ship), but then I had to focus on my Marvel Big Bang fic, and then I had plans to finish it by Christmas as an actual gift for Lise and also so I could say "hey it's kinda sorta for HolidayStoking now," but then I had to focus on Yuletide so it didn't happen then either, and now it's Lise's birthday (it was when I posted it on AO3, anyway, about a week ago) and I decided I am_ going to get this damn thing done _because it's taken WAY TOO LONG for what should have been a fairly simple concept._

 _Fic title is from the New Pornographers song "Up in the Dark." Are the lyrics generally relevant to this fic? HMMMM I wonder_

* * *

Steve wonders, as he stares panting down at the corpse of the Mad Titan, if he's ever going to get an important victory that doesn't feel achingly hollow in one way or another. When he captured Zola on that train, he lost Bucky; when he took down Schmidt, he lost everyone else. Loki and the Chitauri invaded and a lot of agents died, including Phil Coulson, who could've been a friend once he got past his hero worship.

And now, they've saved not just Earth but the whole universe, possibly in more than one reality, and all the Avengers and most of their allies are injured but alive, which is better than anyone could have reasonably hoped for under the circumstances. Steve can barely muster up a sense of relief, because this time, the casualty was Loki himself—Loki, who started out as their enemy until the scepter's control over him broke and everybody learned about Thanos, who'd been tortured into compliance and still did his best to sabotage his own invasion, who became their tentative ally the moment he started telling them everything he could about the Mad Titan. It's like some kind of cruel cosmic joke, that the man who brought them together as an enemy would become their teammate and friend only to be torn away just as Steve was cautiously beginning to consider the future.

Loki himself would probably consider it a joke, anyway, because he appreciated awful ironies with a kind of gallows humor that Steve sometimes shared. But this time he can't, because he's gone, and all Steve can think is an exhausted _damn it, it's not fair_.

* * *

He doesn't know when, exactly, Loki went from asset to ally to friend, and now that it doesn't matter, he wants to pin it down, as if that would change anything. There was an uncomfortable transition period in the beginning, for a little while, where Loki mostly stayed in a secure apartment in the Tower (Thor had flatly refused to hand him over to SHIELD custody, and as much as it made Steve uneasy at first to live down the hall from the alien who tried to conquer Earth, he had to agree that trusting SHIELD with any alien was probably a bad idea) and wrote pages of information on Thanos and his forces, and they only ever saw him at the almost-daily debriefing sessions. He cooperated with everything, answering any question he could and making educated guesses when he wasn't sure, and Steve was impressed despite his own misgivings by how professional Loki was about all of it. There was no more posturing, just concise reports about Thanos and his armies.

Thor corroborated what he could, which wasn't a lot; Asgard's queen was able to fill in a little more from history and legends, once everything had been explained to her. (With the Bifrost still under repair, Frigga could only project her image rather than visit in person. The first time it happened, Steve had some real concerns that Tony was going to have a stroke trying to figure out the science of it—or at least, that was easier and more polite than thinking about the way Frigga's composure broke, just for a second, on seeing her lost son again and seeming to understand what he wasn't saying, or how Loki's expression went vulnerable and _young_ just as briefly before smoothing over into a practiced mask and he disappeared for the rest of the day after Frigga had to leave. Steve found himself missing his own mom, with a sharper ache than he'd felt in years, and he thought he understood Loki a little better, after that.) Loki started working in the lab with Tony and Bruce, too, experimenting with ways magic and science could work together to create some kind of effective weapon, and for a couple weeks that was it—he kept to himself except when he was specifically needed.

Then the dreams started—nothing concrete for Steve, or at least nothing he could remember beyond a vague sense of dread, and the others reported something similar when he asked. Three restless nights later, everyone living in the Tower was jolted awake around 3 a.m. and nobody was quite sure what they'd heard, but after a few minutes JARVIS passed along a message that Thor and Loki were requesting all Avengers' presence in the common room on their floor.

Thor was still in his pajamas, like everyone else; Loki was fully dressed and looked perfectly composed, if you didn't notice the bruise-like smudges under his eyes or the way his face was somehow several shades paler than usual. He told them, briefly, that Thanos was making his move sooner than expected: that the dreams they'd all had were taunts, that the Titan was now confident he could break into the Nine Realms without the Tesseract, that they had a few months at best rather than years as he'd previously assumed, and that the best option was to take the fight to him instead, as quickly and forcefully as possible. Without giving any of them the chance to voice the suspicion he apparently expected, Loki added that he and Thor had already been in contact with Frigga, who confirmed that she and many other Asgardian mages had experienced similar visions and Heimdall had sensed increased activity from the area where they thought Chitauri space was located. Repairs to the Bifrost were an even higher priority now, and representatives from Asgard would visit to coordinate strategies as soon as possible.

After that everything got a lot more urgent, and they all started seeing a lot more of Loki, because there wasn't time anymore for any of them to keep a polite distance. For his part, Steve found himself increasingly impressed by Loki's tactical and strategic thinking as the debriefings turned into complicated planning sessions. His ideas tended to be a little unconventional, whether they went toward the more short-term goals of securing the other Infinity Stones and undermining Thanos' alliances or the slightly more long-term plan to attack Sanctuary, but they made perfect sense when explained. (The first few times Loki offered a plan like that, his shoulders tightened a little like he was bracing for rejection, and when it didn't happen, his expression flickered with a fraction of a second's surprise. The first time Steve complimented one of Loki's ideas, he saw genuine disbelief before Loki masked it. He hadn't really thought about it in advance, just made an offhand comment, but Loki's reaction by itself filled in a bit more of the picture, especially when Steve knew what that was like, being ignored or pushed aside or talked over.) More than anything, those strategy meetings cemented for Steve that Loki really had been trying to sabotage his own invasion, because the plan he'd used was incredibly sloppy in retrospect and nothing like what seemed to be his usual style. And his usual style, to be honest, was something to admire.

The other thing was, Steve had freed enough prisoners during the war to know what long-term trauma looked like. With Loki, it was easy to forget, because he seemed so polished and composed all the time—always elegant, in a way that almost made Steve feel a little big and ungainly again, at first. They all understood he'd been tortured, even if he hadn't used that word, and it was obvious he didn't want to go into much detail about the specifics of his time at Sanctuary, but he was good enough at talking around it that Steve kind of assumed he was well on his way to putting the whole thing behind him. Asgardians had to be mentally as well as physically resilient, he supposed, and for all he knew maybe it wasn't that big of a deal for them—unpleasant, but memorable more for the insult of having been temporarily forced to serve someone unwillingly than anything else.

He knew better, when he thought about it, but he didn't really have a reason to, for a little while. Then he found Loki huddled in the stairwell, a good hour after the strategy meeting had ended, his back pressed into the corner so hard that Steve's spine ached in sympathy just looking at him. His hands were shaking where they were clenched around his pulled-up knees, and even though he was gasping for breath like his lungs wouldn't work right, he was almost completely silent. As if his life depended on staying quiet, or he'd been taught that making a sound meant pain.

Steve knew what trauma looked like, what a flashback-induced panic attack looked like—he knew what a panic attack felt like, for that matter. He didn't have panic attacks often, but it happened, sometimes, ever since the ice. The first time, he thought it was his asthma coming back despite the serum, and he wouldn't wish that crushing sense of fear and helplessness on anyone. But this was _Loki_ , elegant alien prince who'd basically brushed off a Hulk-smashing, and Steve's brain sort of froze for a second in surprise, jarred by the wrongness of seeing him like this. He hesitated on the stairs and thought about getting Thor, because this wasn't his area and he barely knew how to act toward Loki at the best of times, but then Loki flinched against the wall and stared up at him, starting to hyperventilate, and there was no way Steve could walk away from the unreasoning terror in his eyes, not even long enough to find Thor.

So he stayed, and talked Loki down, and in the process learned a little more about the things Loki had decided weren't relevant enough to tell them, like what Thanos did to him, and that he was barely holding it together every time he talked about the Titan. Like his shame at Steve seeing him that way, and his self-disgust for what he saw as weakness, and that's probably when Steve went from just appreciating his information and his often brilliant tactical mind to wanting to _help_ him as a person, not just a valuable asset.

So he convinced everyone to try letting Loki join team meals and movie nights, and the first few times were awkward as hell. It got better once Loki proved he could cook and that he was good at remembering how everyone liked their coffee or tea (not that he always respected their preferences, once things got a little less strained, but at least he usually had a reason). Steve invited him to spar, and once he established he meant it when he complimented Loki's fighting style, it turned into a regular thing, one he looked forward to as a refreshing change from the strategy meetings and technobabble. Loki was adaptable and graceful, and he couldn't quite let loose even with Steve, but he was better than Thor at walking the line between holding back too much and too little in his sparring matches, which meant Steve finally had a proper partner for practicing hand-to-hand combat and even learning new moves.

And then post-sparring snacks became a thing (Loki discovered he loathed sports drinks and introduced Steve to the Asgardian equivalent, which was light and bubbly and definitely enough to make him swear off Gatorade forever), and experimenting with various kinds of Earth food, which was often as much a discovery for Steve as it was for Loki. Thor had fun with new food too, but he also seemed willing to eat anything. It was pretty much the same with pop culture; Thor liked whatever they showed him, but Steve had a lot of catching up to do, and it turned out Loki was insatiably curious about basically everything—so that became a thing too, Loki and Steve working their way through movies and books and documentaries that didn't interest the others or that they'd already seen, with Loki often adding sharply witty commentary that surprised a laugh out of Steve nearly every time. (With Loki, he was laughing more than he had in…well, it sure seemed like a while.)

There wasn't much to laugh about in general, of course, not with a death-obsessed alien eager to get started destroying the universe. Outside Stark Tower, life went on and nobody knew a real apocalypse was coming, one that would make the Chitauri invasion look like the warmup exercise it really was, but among the Avengers, it was there whether they were talking about it or not: that Thanos was coming sooner or later, and they'd only get one shot to stop him before he destroyed everything, and if they failed he'd probably take them prisoner just to make them watch their planet burn. Steve knew tactics and strategy, knew how to adapt to bizarre new situations straight out of sci-fi movies, but this was on a different scale with wildly different weapons, not just sci-fi but _magic_ , and it didn't take long for him to feel out of place.

Tony, Bruce, and Loki were doing the bulk of the work, after all, bridging the gaps between science and magic to create a weapon fueled by both, and Steve had nothing to contribute to that effort (aside from making sure they all ate and slept, and intervening on the relatively rare occasions that Loki or Tony got too frustrated with a setback to remember that needling the other was a bad idea). He could plan, a little, and train with simulators and new weapons, and go for runs or murder punching bags until he was exhausted, and check in on everybody, but he couldn't help build the thing that might save them, and he couldn't let anyone else see just how much he had to wear himself out to stop thinking about Thanos for even a few minutes. Captain America was still a symbol, even to people he'd come to consider real friends, and a good symbol did his job to keep morale up and always project calm confidence.

But Loki already knew what they were facing, personally, and somehow that made it a little easier to set everything aside for a little while with him. He was pretty sure it was good for Loki too, being able to focus on something harmless, something that didn't involve Thanos and the weapon that was supposed to stop him. It still came up, of course, partly because sometimes Loki needed to vent, and Steve couldn't help much with the magical or technical problems, but at least he could listen. He thought it sounded dangerous as hell, mostly, and uncomfortably similar to Schmidt's weapons and SHIELD's Phase 2, but given what they were facing, he couldn't fault anyone for turning to the Tesseract again. They were using nearly microscopic bits of it to power the device Tony insisted on calling the Titanbuster, to Loki's irritation, along with equally tiny particles of the stone from Loki's scepter and the other Infinity Stones they (mostly Loki with a little help from others on Asgard) had managed to locate. Steve was _pretty_ sure the experiments weren't going to blow up the tower before they ever had a chance to take the fight to Thanos, although more than once Loki came to him with singed eyebrows and a really ferocious scowl.

After four solid months of effort, the Titanbuster ended up looking more or less like a bulky telescope on a tripod. The prototypes were all ugly and the final product wasn't much better, even with Tony's manufacturing experience, and Steve was pretty sure the lack of elegance annoyed Loki as much as it did Tony, just not as vocally and in different words. It wasn't elegant in the way it functioned, either, which Steve mostly picked up by inference, because that part actually did worry the Titanbuster's creators, so none of them felt like complaining about it in quite the same way. As far as Steve understood it, getting even near-microscopic pieces of Infinity Stones to cooperate without exploding was close to impossible, and the end result required some precise sequential tuning and a lot of Loki's magic to hold the reaction steady. Even then, it would take a little while to power up once Loki got it going, because there was no way to speed up the process and still keep it stable.

But they all knew they were running out of time. Even without the dreams that never quite went away, the reports from Asgard, and the weird readings Jane Foster was picking up on some of her instruments, Steve would have known it. They were hurtling toward something inescapable, all of them, and it felt like that last plunge into the ice.

None of them could sleep, the night before the final battle, but they all had different ways of dealing with it—Clint and Natasha sparred with each other, Tony locked himself in his workshop with loud music and a lot of Red Bull, Bruce meditated and probably drank a couple gallons of herbal tea, and Steve found himself in the common room again, too edgy to sit still. It was stupid and impractical and he knew better, and he still couldn't make himself settle long enough to take even a short nap.

Loki found him there, and he looked so perfectly put together at 2 a.m. that it had to be an illusion (either the magical kind or the mundane kind that Steve knew all about, because Captain America didn't have the luxury of ever being anything less than confident). He made hot chocolate for both of them, dragged Steve over to the couch, and called up some Monty Python, and if neither of them were inclined to find it as funny as usual, at least it was a distraction. At some point Steve must have even fallen asleep, because when he came alert to the sunrise leaking in through the half-darkened windows, the TV was off and he was definitely slumped against Loki's side.

And Loki was looking at him, something in his gaze that was simultaneously fierce and devastated, protective and _lost_ , and for the space of a couple heartbeats Steve was positive that Loki was going to kiss him, that he _wanted_ Loki to kiss him.

But he was awake, and Loki's expression settled into something more neutral, with a wry smile and the teasing implication that Steve might have been drooling a little in his sleep, and the moment passed.

There was no time to pause after that, before they gathered on the roof of Stark Tower and the newly repaired Bifrost whisked them off to Asgard, or after, in the last-minute strategy meetings with Asgard's generals. And then they were standing in Heimdall's observatory, the Avengers and Thor's warrior friends and Loki, with a good portion of Asgard's army waiting on the bridge behind them, and as Heimdall opened the Bifrost, Loki stepped up to the widening portal and ripped it inside out.

The actual passage through the nowhere-space Loki had opened might have taken forever or no time at all, a confusing space of mostly blankness that Steve's brain didn't seem equipped to process, and then they were through, standing in what Loki had described as a temporary pocket dimension overlapping Sanctuary. Asgardian soldiers appeared around them, a few at a time, and finally Loki made another twisting gesture and everything—shifted, reality sliding sideways into focus, and the battle began.

The place was swarming with Chitauri, but just as planned, the Asgardian soldiers had the advantage of surprise, leaving the Avengers free to strike at Thanos himself. The Titan wasn't hard to find, in the end, sitting in a floating throne inside a huge chamber near Sanctuary's highest point, just as Loki had predicted. The chamber was full of Chitauri like the rest of Sanctuary, only these weren't just cannon fodder like so many of them.

"Well, Laufeyson," Thanos said, smiling. "Did you bring me a sacrifice? If they die well, perhaps someday I will grant you the mercy of joining them."

Loki's hands trembled on the Titanbuster, very slightly, but he avoided Thanos' gaze and started feeding it his magic, and there was no more time to think, just to group up around Loki to protect him and the weapon from the Chitauri. It was like New York all over again but worse, now that he knew how high the stakes really were and every time he looked up he saw Thanos watching, impassive, almost amused by their efforts. He was not going to panic at a little bit of death, after all, not when he had plenty of Chitauri to sacrifice and definitely not when it was his former thrall trying to take revenge.

"He does not fear me," Loki told them at the final strategy meeting, with something like a very grim smile. "He does not fear Midgard and her Avengers. We shall teach him otherwise."

Seeing Thanos for the first time, Steve had to wonder if that was wishful thinking, a half-broken survivor's desperation to convince himself that his captor hadn't completely destroyed him. There was something viscerally terrifying about Thanos, the implacable coldness in his eyes, the way he smiled down at them, and it occurred to Steve that Loki had never once admitted that the Titan scared him. He tried to hide it, even, but it was pretty obvious all the same if you were paying attention, which Steve was, so he could say with some certainty that Loki was terrified of Thanos. Seeing the Titan in person, Steve found himself wondering what kind of iron control Loki had to keep from showing more fear than he did, because just looking at Thanos was like…like staring into the void at the end of the universe. He thought he understood, then, what people meant when they talked about monsters. This guy made Red Skull somehow look like a kid playing dress-up.

But there was no turning back, and anyway he'd never run from a fight before. He sure as hell wasn't going to start now, especially with Loki right behind him, white-faced and rigid with tension under the gaze of the being who broke him but never once hesitating as he primed the Titanbuster.

It was like New York all over again, the Avengers barely holding their own against a seemingly endless onslaught of Chitauri—until Loki shouted "Stark, your turn," and then it wasn't like New York at all. Green light flashed out from Loki's hands, flinging the nearest Chitauri fighters into the walls, and Tony triggered the last of the sequence to fire the Titanbuster—

—and the damn thing _worked_. The barely visible shield of the Titan's power flashed and then _cracked_ , and he actually staggered as his throne crumbled beneath him. Loki's sudden wild grin matched what Steve was feeling, disbelief and hope rising up in his chest that they were going to do the impossible and take out one of the most powerful beings in the universe, that for _once_ they were all going to survive. It was a distraction, always a distraction, when he needed to focus on concrete strategy and tactics and the shield rebounding into his hand, but he couldn't help the flash of it as Thanos dropped heavily to one knee behind his flickering shield. If they could keep off the Chitauri long enough for the Titanbuster to recharge and hit Thanos one more time—

And then the Titan _smiled_ , and something that looked a lot like the Infinity Gauntlet materialized around his upraised fist, with a single glowing red gem on the back. Steve had about half a second to remember Thor saying that Asgard and her allies had found and safeguarded most of the Infinity Stones, and Loki pointing out that _most_ was not _all_ , and the best they could do was hope the final stone remained lost, because even a single Infinity Stone in the Titan's hands could undo everything. There was a flash of blinding light that made Steve jerk back on reflex, and then something like a _spear_ of it lancing outward, and Steve knew it was going to hit him before he could get his shield up.

Instead something—some _one_ —slammed low into his side and sent him flying. Steve scrambled up and there was Loki, sprawled on his back and drenched in blood, one arm nearly detached and his entire torso charred beyond recognition but still moving as he struggled to breathe.

"No," Thanos growled, "you are not worthy of my lady." He made a strange twisting motion with his gauntlet, and Loki's body disintegrated.

There was a part of Steve's mind that just _stopped_ , caught somewhere between pain and denial. The rest of him—Captain America, who knew how to compartmentalize, who understood the need to keep moving and finish the mission—shut that away and reacted without a pause for thought, seizing on that tiny window of the Titan's distraction. He lunged for the gauntlet, and so did Thor, roaring wordlessly, and Mjolnir and the shield smashed together through the joint of the Titan's elbow.

The gauntlet hit the floor with the massive hand still inside. Steve reversed his swing and knocked it away, and Thanos howled and struck out with his remaining arm, sending both of them flying into the nearest wall. But by then it was too late: Tony had already powered up the Titanbuster for another blast and this one hit Thanos square in the chest. The light shattered his armor, sank into his skin, radiated explosively outward from the impact point—and Thanos hit the ground face first, his whole body shriveled and still glowing slightly.

For a long moment the chamber was silent, and then Tony said, "So we did it, right? He's actually dead? Somebody check, the bad guys are always getting up and walking away when you think they're down for good—"

He was interrupted when Sif burst into the chamber, saying breathlessly, "The Chitauri all collapsed, the link must have been severed—" She stopped short, staring. "You did it."

"Yeah," Steve said. Everything inside him felt _heavy_ , like reality was weighing him down as it finally caught up to him. He climbed to his feet and offered a hand to Thor, but the thunder god didn't seem to notice, his expression almost blank with shock. "Yeah, we did it."

* * *

It didn't feel like a very good victory then, and now it feels that way even less, several minutes later, after Tony's packed away the gauntlet and the Titanbuster and he and Bruce are setting up the stasis field for the Titan's body. Thor's friends have taken charge of the mop-up operation (guaranteed to involve some serious work even though the Chitauri are all dead), leaving the rest of the Avengers at loose ends. Thor, having given a few basic orders to the Asgardians, seems unable to pull himself away from the spot on the floor where Loki's body was. There's some blood and a huge scorch mark, but nothing really tangible left behind, and Steve's heart twists at the lost expression on his face.

"Thor," he says, as gently as he can. "We should probably get started on clearing out of here."

Thor looks up slowly, his eyes red-rimmed but dry, seeming almost numb with grief. "This is the second time I have watched him die. I…he died a hero, worthy of Valhalla, but I…how can I—" He drops his head, swallowing hard.

"I'm so sorry," Steve says. He should say more, wants to say more, but he has no idea what.

"As am I," Thor says dully. "He was your friend too. I was…I am glad of that."

"We'll tell everybody," Steve promises. "That he was a hero and a good person. It shouldn't be like this, but Earth and Asgard at least need to know. We can…we'll make sure he's remembered the right way." It's all he can think to offer, and he knows it hardly matters, not when he can barely wrap his own head around the idea that he'll never hear Loki laugh again.

"Asgard," Thor says, and then his expression crumples. "I must tell Mother. I…oh, Norns."

Steve hesitates, not sure if it's appropriate, but— "I'll go with you. If you want."

Thor clasps his shoulder. "Thank you, my friend. I should…" He drops his hand, still staring at the floor, and after a moment he clears his throat. "Heimdall. Tell the king and queen that we must meet with them privately. We will…we will be there shortly."

It takes a little while, still, because Thor has to oversee the transport of the Titan's body and the gem in his gauntlet, handing both over directly to Odin, who has already received reports of the battle and looks about as stunned as Thor does, just more subtly. Eventually the Avengers are all back on Asgard, most of them gathering in a very subdued group in Tony's suite while Steve and Thor go to the royal family's chambers. Frigga is waiting for them, the picture of calm except for the way her fingers twist where she has clasped her hands in front of herself.

"Thor," she says, and her voice does not shake, not at first. "They tell me…"

Thor bows his head. "It is true, Mother. Thanos is defeated, but Loki…he fell in the battle. Thanos had one of the Infinity Stones."

Frigga squeezes her eyes shut, swaying slightly. "Oh, my child."

Steve says, "If there's anything the Avengers can do for you, or…Earth in general…" He trails off. Differences in advancement aside, nothing anybody can do will help this.

Frigga glances in his direction, her gaze almost blank, but then she focuses on him. "He saved you."

"We never could've beaten Thanos without him," Steve says. "He saved _everyone_."

"No," she says, intent now. "He saved you, personally. That was how he—what happened, exactly?"

"Mother," Thor says, but she puts a hand up to stop him.

"I am not some infirm old woman you need to coddle. Tell me, Captain Rogers."

Steve straightens, and tells her. For a long moment she says nothing, frowning, and Steve starts to repeat helplessly, "I'm so sorry—"

"Those were his exact words," Frigga says. "Thanos. 'You are not worthy of my lady.'"

"Yes ma'am," Steve says. He swallows. "I know there isn't really anything I can offer, but…but if there's anything I can do…"

"In fact, I believe there is," Frigga says. "You may yet have a chance to save Loki."

Thor frowns. "Mother?"

"Well, _think_ , Thor," she says, a little sharply. "Thanos said Loki was not worthy of _death_. It follows that he is _not dead_."

Steve would really, really like to believe that, but— "Thanos…vaporized him."

Frigga crosses her arms, expression hardening into resolve. "With one of the Infinity Stones, the exact properties of which no one has ever entirely understood but which are all capable, in one way or another, of _reshaping reality_ , and there is no way to say how long it was in the Titan's possession _._ It is just as likely—more likely, even—that Thanos sent him somewhere to suffer, perhaps a place he created for that exact purpose before the battle. Heimdall would not be able to see or reach him, but—" She turns to Steve, and it takes a good share of his willpower not to flinch under the intensity of her gaze. "Loki's last act was to lay down his life for yours, and doing so would have created a bond that we can follow to him."

"I don't have magic, or anything…"

"No. But I can read what is there, and I can set you on the path, as long as the connection is strong enough." She raises one hand. Steve braces himself, not sure what to expect, and jerks anyway at a sudden strange sensation in his chest, like somebody just tugged on a string tied to his sternum. Frigga nods, looking grimly satisfied. "It will hold. If you can reach Loki, wherever he is, Thor and I may be able to follow you. The only question is whether you are willing to do this. I cannot say where Thanos has placed my son, but I am sure it is nowhere pleasant, and journeying there could be dangerous for you."

Thor turns to him, and the sudden hope in his eyes is downright painful. "My friend—I do not ask you to do this, but—"

"Yeah," Steve says. He doesn't even have to think about it. "Loki's my friend too. Of course I'll do it. Whatever you need. Just…point me in the right direction."

Thor sweeps him up in a crushing embrace. Frigga is much more restrained, but her relieved, grateful smile is almost dazzling.

"Do I need to do anything?" Steve asks, suddenly nervous.

"No," Frigga says, resting her hands lightly against his temples. "Only close your eyes and let me guide you."

He does. Her fingers are cool against his skin, tingling slightly, and he focuses on that as the strange tugging sensation takes hold under his breastbone.

"Now walk," Frigga says, except he is almost certain he isn't hearing her with his ears. Steve takes a blind step forward, then another, and by the time he's walked half a dozen paces, he knows he's alone. There's no more breeze in the windows, no movement nearby, just the sound of his own breathing.

He opens his eyes and immediately wishes he hadn't, because it's just as dark this way—darker even, somehow, like straining to see anything makes it worse. For a second he can only stand there, paralyzed by formless, visceral dread. He's never really been afraid of the dark, not since he was a kid, but this is…nothingness, absence, _wrong_ , and all he wants to do is turn around and run back to the light of Asgard.

And maybe he could, if he did it now, but it doesn't matter, because he isn't going to run away. He takes a deep breath to remind himself that he can, refuses to look over his shoulder to see whether Asgard is still there, and follows the tug of magic onward into the dark. There's _something_ under his feet, at least; it doesn't feel like any surface in particular, but it exists and he can walk on it, so he does.

Gradually, so gradually he has no idea when it started to happen, the nothingness takes shape around him. First there is the suggestion of space instead of the lack of it, and the hint of something solid under his feet. Slowly it becomes rock, crowding in closer to form a tunnel, and as reality settles into place around him, he steps into a cave. He can see the rough stone under his boots now, but no more than a foot or two in any direction—past that, everything is darkness.

Steve stands still for a moment, trying to orient himself. Not far off, something is dripping, and he turns in that direction for lack of any other guidance. And then the steady _drip, drip, drip_ is punctuated by a hiss, almost like oil sizzling in a skillet, and a drawn-out breathless moan. It shouldn't be possible for him to recognize that voice, because it's weak and ragged, almost an animal sound of pain, but he knows it anyway.

"Oh my god, Loki," he says, rushing forward almost before he realizes he's moving, and suddenly he's close enough not just to hear but to see, and he wants to be sick.

The tug of magic inside him knows that this is Loki; without that, he's honestly not sure how he would tell. The man lying naked and chained to a rock is tall and thin, but there's no more lean muscle, just the emaciated frame of a starved concentration-camp victim, and his hair's so bloody it's impossible to say for sure what color it is. And his face—he barely has a face anymore. Most of his skin is gone, burned or melted away, leaving behind red wet muscle like Schmidt but so much worse, because at least Schmidt's face was whole. There's bone showing in places, especially along the ridge of his cheekbones, and his eyes are little more than bloody sockets.

Almost as an afterthought, Steve's brain finally latches onto what should be immediately obvious. The prisoner is a deep blue color, where his skin isn't eaten away or completely obscured by blood, and it takes Steve a second to realize that he's seeing Loki's Jotun form for the first time. Under other circumstances he's pretty sure he would find it beautiful, but right now his mind has no room for anything but horror at the wreck of Loki's body. There's some especially awful bruising around his left shoulder, and the joint itself looks warped, the arm nearly limp—because he must have dislocated his own shoulder in his struggling. His right thumb looks like it's out of joint too, that one probably on purpose in an equally futile effort to slip his hand free of the shackle. Worse, the pale gleam of bone is visible across his already prominent ribs, and Steve realizes with a sickening lurch that the tiny twitching movement he can see in Loki's chest is the beating of his heart.

From somewhere above Loki, a droplet of something dark and glistening falls to land on his abdomen. It eats into his skin like acid, making the source of the hissing noise suddenly and horribly clear, and he chokes on a sob of breath, pulling weakly against his chains. His skin looks almost flayed where the cuffs bite into his wrists and ankles, and blood drips steadily into little pools on the floor. The bottoms of his feet are bloody ruins, scraped raw from all his fruitless attempts to gain enough leverage to twist out of the way of the acid.

Steve starts to reach for the chains and stops himself short, fist clenching. _Don't rush in. Assess the situation. You might make this worse_. The shadows above Loki move again, drawing Steve's gaze upward, and he sees—he doesn't know what he sees. Something vast and sinuous, something that is not quite _there_ no matter how hard he looks at it, like it's flickering just on the edges of what his brain can process, and the acid it drips is the same, chewing away tiny bits of reality as it eats through Loki's flesh. Steve suddenly remembers reading _The Fellowship of the Ring_ with him and its descriptions of what the Morgul blade did to Frodo, working its way toward his heart to turn him into a wraith, and now that he's thought it, he can't get the idea out of his head of the acid sinking into Loki's veins and devouring him from the inside.

The chains, too, are—wrong, somehow, when he takes a closer look. The acid has marked Loki's body near each cuff, but the metal itself is undamaged, not even scratched where Loki's struggles have scraped it against rock, and trying to focus on it makes Steve's head hurt. He knows, with abrupt and absolute certainty, that he won't be breaking them by any ordinary means. If Thor manages to follow him with Mjolnir, maybe, but otherwise…

Well, there's nothing he can do about that now except hope somebody on Asgard pulls through. All Steve can do is try to help Loki. He unfastens his helmet, pulls it off, and holds it out to catch the acid. The next drop falls, glittering, and strikes the inside of Steve's helmet. There's another hiss on contact, and within seconds, the acid eats through the tough material of the helmet and hits Loki's sunken stomach. Loki moans again, straining at his bonds as acid chews through skin and muscle, and Steve catches a brief glimpse of shiny viscera before the new wound fills with blood.

"Okay," he says, his voice a little shaky in his own ears. "That didn't work." He drops the helmet and slides his shield off his back, the only thing he has left to try, and holds it out in both arms like a giant flat bowl. The next drop hits, and the next, and the next, and the acid eats through the straps, but the vibranium holds. Below the shield, Loki goes limp on the stone slab, panting.

"Okay," Steve says again into the sudden silence. "Okay. I can do this."

For several long moments there's no sound but Loki's rough breathing and the slow drip of acid into the shield. Then Loki shifts, his head turning like he's still trying to see, and he slurs, "Oh. Thas'…better."

"Glad to hear it," Steve says, as cheerfully as he can manage. At least Loki isn't so far gone that he can't register the absence of fresh pain.

A pause, then: "Cap-tain?"

"That's me." His arms aren't getting tired yet, but it's already an awkward position, and he's not sure what he's going to do once the little puddle of acid gets bigger.

"Steve," Loki says, a little more clearly, although he still sounds pretty out of it. "That's…good. You are…a good man."

"Just trying to help," Steve says. "Do you have any idea how long you've been here?"

Loki tilts his head, grimacing. "Don't know," he says, voice blurry. "Feels like...a long time."

Steve has his own guess, at this point, and he doesn't like it at all. Loki's blood is everywhere, coating the stone slab and the ground below, and as far as Steve can tell, some of the blood is pretty old—even rotting, judging by the smell that nearly gags him as he tries to get a closer look. That, as much as the wasted condition of Loki's body, confirms that he's been here a lot longer than the handful of hours since the battle. It might mean Steve's journey here took way longer than it seemed to, which isn't an encouraging thought for chances of rescue, or that Thanos crafted this place in a way that was somehow separate from the normal flow of time, which…is also not an encouraging thought. If it's something on the order of a week in here for every hour outside—or worse, maybe a lot worse, maybe more like a month—then he might not be able to do much at all.

"Well, don't worry about it," he says aloud. "The important thing is, the plan worked and Thanos is dead, partly because he let himself get distracted to send you here, and…now I'm here, because your mom was right, you saving me meant I could follow you."

Loki makes a vague humming noise. "Undone by…his contempt for me. Almost…poetic. I would…like to…believe..." He trails off, seeming exhausted by those few words.

"It's all done," Steve says. "You did great, and you helped save everybody. So—just rest now, okay? I've got you."

"You do," Loki murmurs. He lets his head roll to the side again, and he can't close his eyes, but for several minutes he stays silent, just breathing. Steve hopes he's getting some real rest, for the first time in…probably a long time.

"I loved you," Loki says suddenly, and lets out a huff of almost soundless laughter. "Funny, isn't it? That something like me would presume… But I did, I think. Might have told you, after, if…there was anything after. This is…better. This way."

"You're telling me now," Steve says, not sure what else to say.

"Am I?" Loki muses. "Hm. Perhaps. But you will never hear it, and that is…better. I am…too much a coward to tell you and risk your disgust, no matter how quickly your kindness would drive you to hide it, and…you do not…you are kind, always, and…I would not wish to put you in that position. You deserve…better."

Steve's fingers tighten reflexively on his shield. There's too much here to pursue at once, and he's not even sure exactly what Loki means (although all the possibilities coming to mind make his chest ache). "Loki," he says carefully, "why do you think I'm here?"

Loki smiles, and his lips crack and bleed. "You are not. But if my mind has finally…lost its grip on reality in favor of a much pleasanter fiction…I am not inclined to complain."

Well, that explains why Loki didn't seem surprised to see him, but it hurts in a way Steve can't quite identify, that Loki's quicker to assume he's hallucinating than that anyone would actually come looking for him. It's on the tip of his tongue to argue that no, this is real, he's really here and he's not going anywhere, but he bites back the words, realizing it might be kinder to let Loki keep thinking he's just a delusion. Because this, catching the acid and talking a little, is the full extent of what Steve can do, and he has no way of knowing what's going to happen in the long term. False hope for a rescue that might never come is nearly as cruel a torture as what Loki's already going through, and if Thor or Frigga can't make their way here, there aren't any good promises Steve can make either. Maybe he'll just…stay here, forever, kept alive as long as Loki is, and that would be all right—but the more likely outcome is that eventually he'll die, either from making a mistake and spilling too much acid on himself or from simple thirst and hunger, and then Loki will be alone again. If nothing else, he can have this reprieve without anticipating its inevitable end, as long as Steve lets him have this.

So instead he tries to smile, hoping Loki will hear it even if he can't see, and says, "Glad to hear I at least rank as 'pleasant.'"

"To be fair," Loki says in a distant cousin of the dry tone that accompanied most of his acerbic comments, "you have…very little competition…at the moment."

"Your flattery needs some work," Steve says.

More seriously, Loki says, "It is not flattery to speak of…your goodness, your kindness, your…your strength. Not what the serum gave you but what you…always had. Your will, your spirit. To…see so much evil, and…still remain a truly good man."

Steve shifts uncomfortably. "I'm really nobody special."

"You are," Loki insists. "You are a warrior, and you could…force others to bend to your will. But instead—you protect. You…save those who cannot save themselves."

"You saved _me_ ," Steve says. "You probably shouldn't have, but you did."

Loki huffs out a nearly soundless laugh. "It was an impulsive act. Foolish." His head lists to the side, and Steve thinks his eyelids would be drifting shut if he still had them. "I do not regret it in the slightest. You are—needed. Because of who you are. Selfless, and _good_ , and… And you are…careful. Not thoughtless with your strength, like…so many warriors. That is…few have such strength of…will, and character. I still…do not understand why you tolerate my presence. More than tolerate, it seems. I have…so often wondered… I am grateful. But I never understood…why."

"I don't _tolerate_ you," Steve says. "I've considered you a friend for a long time now." Loki makes a noncommittal sound, and Steve holds back a sigh, because of course nothing he says will make a difference when Loki thinks he's a hallucination. "I like you. Honest. You're funny and smart and you're capable of so much more than you think. And you're—tough. _Brave_. To come after Thanos with us after everything he did to you? That takes real guts. Nobody would've blamed you if you couldn't face him."

Loki turns his head again, almost an uneasy gesture this time. The bloody ruins of his eyes look like they've already healed a little, but he's nowhere near being able to see again. "I merely…I wanted vengeance. It was…not selfless."

"Maybe not," Steve says, "but it's still more than a lot of people would be able to do, and you helped save the universe while you were doing it, which I figure counts for something. And you saved me. You could've figured I was an acceptable loss and honestly I would've been, given the alternative, but instead… And now you're here, _because_ you saved me. So yeah, I'd call that pretty selfless."

Loki exhales, fingers flexing restlessly in the shackles. "I…do not…"

The next drop hits, and by now the pool of acid in the shield is deep and wide enough that the splash sends a tiny droplet over the edge and onto Steve's left arm. The tough material of his suit only protects him long enough to think _oh shit_ and try to brace himself, and then agony blazes up his arm like somebody's jammed a red-hot poker into the bone. For a moment all he can do is cling to the shield and struggle to keep his feet, the entire world narrowing down to the feeling of molten metal burning through his forearm. The worst pain fades after a very long moment where his ears are ringing and he's gasping for breath, and even then his whole arm _aches_ and the muscles won't stop twitching.

"Steve?" Loki asks uncertainly.

"Sorry," Steve says. "Sorry, I gotta…dump this out. Shield's…getting too full. Back as soon as I can, promise." He pulls away, carefully, so carefully, stifling the urge to chuck the whole thing away from himself or just move too quickly and risk spilling it. That much acid at once would do way more damage to Loki than the slow drops. Steve shuffles back three steps, turns smoothly, takes three more steps into the dark. His injured arm is still trying to shake, and the shield is probably putting permanent indentations in his fingers from how tightly he's gripping the edge, and still he makes himself move calmly, carefully, watching the ground and the sloshing acid at the same time.

Behind him, Loki lets out a strangled cry as the acid finds its mark again. Steve controls the impulse to dump the acid in his shield and rush back, instead crouching in another smooth motion and tipping it all out onto the floor where the rock slopes slightly downward. It's less that he's afraid to spill any on himself as much as that he knows it'll be that much harder for him to keep holding the shield if he does. Just as the last of it spills onto the ground, Loki makes another thin, agonized noise that sounds like it was wrenched from him, and finally Steve does straighten—makes himself stop again to check that the shield isn't dripping any leftover acid, and lunges to put it back in place as quick as possible, barely in time to catch the next drop.

Loki flinches as it hits metal, then goes still. "…Steve?"

"I'm back," Steve says. "Sorry. Should be good for a little while now."

"Are you…" Loki swallows. "You're hurt. The venom—"

"I'm fine. It was just one drop and I'm already healing." Well, his arm hurts less, anyway, which could just as easily be nerve damage, but that's not really relevant, and it's definitely not something he's going to tell Loki unnecessarily.

"You're _here_ ," Loki says. "Steve. You…you're not my imagination. You're here."

Steve considers denying it for about half a second and immediately rejects the idea; letting Loki believe something is pretty damn different from actually lying to him, whatever the motive might be. "Yeah, I am."

For a long moment Loki stares blindly up at him, throat working and breath audibly shaky. Then he bursts out, " _Why_?"

Of course _why_ is his first question, not _how_. Steve supposes he shouldn't be surprised, but it's still depressing. "Why—Loki, I don't know how much you remember, but you saved my life. You're here right now because Thanos was aiming for me and you took the blast instead. He's dead because of you, but we thought he'd killed you too, and when we figured out he might've stuck you somewhere and I might be able to get to you, I had to try. I couldn't just—not do anything."

"No," Loki says, tugging fretfully at his shackles in what looks like an unconscious gesture of frustration. "No, you should not _be_ here, you should not have—I am not your responsibility. I made—a free choice. You mustn't…you owe me nothing."

"That's not—"

"The debt is still mine. You have done your duty, more than your duty, now _go_ before this place traps you too—"

"Loki," Steve says loudly, and Loki falls silent, his chest heaving. "I'm not here because I feel like I have to be. I'm here because I _want_ to be."

Loki opens his mouth and closes it again without saying anything. His blank incomprehension would be funny if it weren't so damn sad. "… _why_."

"I know you thought I was a hallucination, but I kind of just told you why. I happen to care about you. You're my _friend_. I don't leave my friends behind," especially not when they're being eternally tortured for Steve's sake, which will put Loki right back onto the responsibility argument, so he doesn't add that part. But hell, Loki already put all his cards on the table even if he thought he was talking to a hallucination; they still might never get out of here, so Steve figures he can do the same (and it's easier, knowing Loki can't see him). "You said you loved me? Well, I don't know for sure if I love you as anything other than a friend, but I think I might, and I'd sure as hell like to find out. And if all I can do for you is—this, then I'm okay with that. So that's why."

"You're a fool," Loki says, but there's no bite to his hoarse voice.

"Yeah, probably. But I've always made my own dumb choices and I don't plan to stop now."

Loki swallows hard, winces. "Steve…"

"I'm here," Steve says gently. "Just…rest. I'll still be here."

* * *

Loki drifts in and out of a restless doze as his body struggles to repair itself. There isn't much visible change, but every little bit of strength he can recover is important, and Steve is determined to give him that as long as he's physically capable. To keep his mind occupied, he thinks through some of the movies they watched, and when Loki's alert enough, he does it out loud. The main result is discovering some really impressive plot holes between the various Harry Potter movies, which gets Loki going (again) on the illogical, inconsistent nature of their portrayal of magic, and for a little while it's almost like they're still in the Tower.

It's impossible to forget the situation entirely, of course. Steve can't even stay in the same spot for very long, because the thing dripping acid (Loki said venom, which makes Steve think bug or snake, and then he remembers one of the most well-known and awful myths about Loki) doesn't stay in one place either. He can't see it moving—still can't actually _see_ it at all, not really—but the drops gradually move up and down Loki's body, forcing Steve to shuffle sideways to catch them. That means he has to stay alert, anyway, which he decides to count as a good thing under the circumstances.

But even Captain America gets tired eventually. When his legs finally start threatening to give out from standing so long in one position, he crouches by the slab, then kneels, bracing his elbows on the stone to keep the shield in position. When his knees hurt too much to stay there, he stands again, joints protesting like they haven't since his pre-serum days.

"You have to rest too," Loki says. "Just—set the shield on my body and take a little while to sleep."

Steve looks down at Loki's torso, still raw and red, bone and muscle still gleaming through the blood, and imagines how it would feel to put any weight on wounds like that. Considers what would happen when the shield inevitably spilled, imagines the acid eating a fist-sized hole through Loki's side and still not killing him. He says flatly, "No."

"Steve—"

"Seriously, I'm fine. I can do this all day," he adds, trying for a smile.

"I rather think you've…been here more than a day already."

"Well, there you go then. Stop worrying about me."

"Someone should," Loki says, not quite sharply. "Norns know you do not."

"Nobody needs to worry about me," Steve says.

"Just because you think no one _has_ since you came out of the ice…does not mean you are invincible," Loki almost snaps.

"That's kind of what Captain America means."

"Then I suppose it is well I am not overly interested in _Captain America_ ," Loki says, the irritation in his tone doing nothing to mask his concern.

 _Interested_ —that's one way to put it. Steve seizes on the distraction, partly because he can feel the very beginning twinges of a cramp in his calf and he needs to think about something else, and partly because he just wants to say it. "Listen, when we get out of here, we should—go somewhere. There's this one coffee shop I like, or—you probably haven't been to any of the museums."

Loki is silent for a moment, long enough that Steve starts to get just a little nervous (which is ridiculous for several reasons), and then he says cautiously, "I would…not be opposed to that."

"Then it's a date," Steve says, and tries not to think about the last time he had a conversation like this. Then, he knew he was going to die; now, he wants to believe there's a possibility of keeping this date, but he knows the chances aren't great. "I could—take you to the Met. Bore you with art history, probably."

"That hardly sounds boring," Loki says. "Perhaps—I could show you some of the palace's artwork, in return. We—the Aesir tend more toward sculpture than paintings, but some of it is…striking. If…you were interested."

"Of course I'm interested." Steve shifts position, leaning some of his weight on the stone slab. "You have any favorites?"

Planning theoretical dates is a good way to pass the time, for a while. But Loki tires quickly, even when it's obvious he's trying to stay awake for Steve's sake, and when Steve has to dump out the shield, every drop of acid that hits Loki's body takes its toll.

And that's how things go for a long, long time. Steve has no idea how long, because his watch stopped working at some point since he left Asgard, but if he had to guess he'd say days, maybe even a couple weeks. His superhuman metabolism seems to have slowed, so at least there's that, and he's gone hungry before. But this is different, time marked only by the drip of acid into his shield, the agonizingly slow healing of Loki's body, and the noises of pain Loki can't keep back every time Steve has to remove the shield to empty it.

At some point, he spills quite a bit of acid on the floor where he's standing, very narrowly avoiding soaking both boots. As it is, he gets some splashed on his feet and legs, and he barely makes it to the other side of the slab before his twitching muscles give out and he goes to his knees. He braces his arms on the stone again to support the shield and hopes grimly that he can go a while longer without really screwing up, because ultimately Loki will be the one who suffers the most for it.

"Steve," Loki says, his voice strained and his breathing ragged. The drops hit the open wounds on his chest this time, and Steve doesn't want to think what the acid might have done to his lungs. "You cannot—you must see to…your own injuries."

"I'm _fine_ ," Steve says through his teeth.

"You remain a terrible liar."

"Part of my charm." He should be able to stand up again, if he gives himself a few minutes first. Probably. "I told you. I can do this…all day."

"You cannot…do this forever."

"The hell I can't." Steve adjusts his position a little, carefully. "And just by the way, I tend to get more stubborn every time someone tells me I can't do something—"

"I _know_ ," Loki mutters.

"—and, you know, every time you try to convince me to let you get hurt more so I can leave or take a break or whatever, the more I want you to know you're worth the effort."

" _Steve_ ," Loki says thickly, unsteadily.

"I'm not going anywhere."

* * *

Neither has said anything in a long time. Steve is pretty sure his body is finally starting to reach some of its limits; he spends a lot more time kneeling than standing, now, and every time he gets up is harder than the last. The muscles in his arms and legs never really stop shaking anymore. He stopped feeling hungry at all a while ago, but exhaustion presses down on him like a weight. Stubbornly he keeps himself awake and steady, but he knows sheer willpower won't last forever.

Then Loki's head turns, like he's trying to look into the darkness on the other side of the stone slab. "Steve," he says hoarsely. "Look."

Steve does. Loki's eyes haven't healed enough to let him actually see anything, but if he's sensing something—

And at first he thinks his eyes are playing tricks on him too, hunger and bone-deep weariness combining to make him see what he wants to, but he blinks hard and it doesn't go away: faint lights, getting closer and more distinct, one the green of Frigga's magic and the other the crackling blue-white of Thor's lightning.

"They're here," he says, hardly believing it himself. "Loki, they're here."

Loki exhales, a little bit more of the tension leaving his body. It turns out his eyes are at least healed enough that he can cry.

* * *

 _To be perfectly honest, I'm not totally satisfied with this fic-originally it was supposed to be a quick little oneshot, so I was okay with the weird/clumsy structure (chunk of exposition to establish the setting before moving on to the bulk of the story), but then as I took longer to get it done, I felt more of a need to expand on the background...without actually wanting to start the story there because this was still supposed to be relatively short setup for the snake-venom situation...so the result is this weird structure BUT LOOK (I am mostly saying to myself, because my self is the one that has a problem with this), it is more important for a thing to be_ finished _than_ perfect _. And hey, at least I put this kinda negative note at the end instead of the beginning, so...good for me not over-explaining/apologizing to people who haven't even read the fic yet?_


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